The Arq completely dwarfs the shuttle in sheer size, but holds less weight and only slightly more volume? Not trying to be a jerk or anything, just one of those things I saw as an oddity. Ignore me if it is intentional.

The Arqueitens doesn't, if I recall correctly, mention have/not having a bay. We gave it one simply as a means to add an additional carrier to the CP list. The bay is intentionally very small as to only allow a few/one ship within it.

The Star Shuttle, is envisioned as a personel transport for moving people/droids/goods.

From the episodes I have seen, it does not show a bay. Note that the wookiee page also does not list one, therefore it has not shown one yet. Now the Venator is similar looking and has tons of bays, but the Arq is much smaller.